The present invention is directed to an assembly for clamping a workpiece in a machine tool. More particularly, the invention provides a means for clamping cutting blades in a sharpening or grinding machine.
In machining operations utilizing a cutting tool, periodic sharpening (e.g. grinding of one or more surfaces of the cutting tool to restore a cutting edge) is a usual occurrence. It is common for the tool, or individual cutting blades thereof, to be removed from the particular machine and to then be positioned and clamped in a mounting block of a holding fixture in a sharpening machine for subsequent grinding. In many instances, such as where different tools or blades are of varying sizes or have shanks of different shapes or sizes, the mounting block must be modified or another installed in the sharpening machine. Such a procedure is time consuming and is usually labor intensive.
One type of known machining operation is the production of bevel gears with cutting tools comprising a plurality of stick-type cutting blades arranged in a cutter head. When the cutting blades are worn to a point where sharpening is necessary, the cutting blades may be removed from the cutter head and then clamped in a mounting block of a sharpening machine holding fixture such as illustrated in U.S. Pat. No. 3,881,889 to Hunkeler or U.S. Pat. No. 4,969,298 to Leutwyler et al. Sharpening of the cutting blades is then carried out by grinding the appropriate surfaces of the cutting blades in order to restore one or more desired cutting edges.
Stick-type cutting blades may vary in size and/or have different cross-sectional shapes thus presenting the likelihood of modifying existing mounting blocks or requiring different mounting blocks in a sharpening machine to accommodate the different blade sizes and/or shapes. For example, a cutting blade having a generally rectangular cross-sectional shank is shown in U.S. Pat. No. 4,575,285 to Blakesley. Cutting blades having more than four sides and including corner angles other than 90 degrees can be seen in U.S. Pat. No. 6,004,078 to Clark et al.
The present invention provides an apparatus for clamping a workpiece in a machine. The apparatus comprises an inner nose portion being rotatable about an axis of rotation and comprising a plurality of mounting surfaces, and, an outer ring portion rotatable about the axis of rotation and comprising at least one clamp operable between an unclamped position and a clamped position. In the unclamped position, the inner nose portion is rotationally positionable about the axis relative to the clamp such that a workpiece positioned against the mounting surfaces may be oriented relative to the clamp to a position at which, with the clamp being operated to the clamped position, the workpiece is clamped against the mounting surfaces. The clamping results in a coupling of the inner nose portion and the outer ring portion whereby with a clamped workpiece, the inner nose portion and the outer ring portion are rotatable together and are positionable about the axis.